For the third time in five months, Israeli luggage held in an ostensibly secure area at the Brussels airport has been tampered with, worrying Israeli and Belgian officials about serious security breaches.

In the latest incident, early last month, drawings of swastikas and anti-Semitic slogans were found inside El Al passengers' hand luggage being held in a "sterile" off-limits area of the airport.

The exterior of some of the luggage was also spray painted with anti-Semitic slogans.

It was the third time in recent months that El Al passengers' luggage has been tampered with at the airport. More ominously, it was the first time vandals deliberately opened baggage to hide anti-Semitic material.

In the previous incidents, the vandals spray painted their racist slogans on the exterior of El Al luggage in September and in November.

This latest incident, which took place on January 3 on El Al flight number 334 departing from Brussels at 8:30 P.M., is more worrisome.

Security officials at the Belgian airport and in Israel are concerned that if the vandals had access to the bags and were able to put material inside, it may be possible to plant bombs on El Al airplanes as well.

Since the incident, Israeli and Belgian security officials have met several times to discuss ways of improving security measures at the airport.

Efforts are also being made to capture the offenders and to identify the security breaches that enabled the vandals to gain access to the luggage.

Officials believe the perpetrators are likely authorized personnel who have access to the airport's off-limits areas.

In May 1999, a similar incident occurred at Madrid airport in Spain, where a swastika was found spray painted on the door of an off-limits room in which El Al stores passenger luggage.